1. Field of the Invention
This invention relates to a rapidly scanned laser system that accurately identifies locations on an object, and more particularly, to a rapidly scanning laser system utilizing a three-dimensional (3-D) data set projected onto contoured surfaces.
2. Discussion of the Prior Art
U.S. Pat. No. 4,883,352 is directed to a galvanometer that scans flat patterns. U.S. Pat. No. 4,883,352 teaches that in critical applications, fine focus control can be accomplished via changes of laser wavelength. The device shown uses quadrant photodetector to actively compensate for relative lateral motion between the scanners and the site being scanned.
The present optical layup template (OLT) can be distinguished by noting that while galvanometer scanning is known, it is the improvements on that type of system which are of significance. The OLT does not use wavelength to control the focusing. It has a fixed focus and fixed wavelength laser. The quadrant photodetector for U.S. Pat. No. 4,883,352 is only designed to compensate for lateral movement. One embodiment of the OLT has at least three (and preferably six) quadrant detectors which will allow for compensation of lateral, depth, and rotational (pitch, yaw, and roll) motions. It is also apparent that the U.S. Pat. No. 4,883,352 system is also optimally designed for projection onto a flat or effectively flat (as seen by the galvanometer scanner) objects. The OLT, in contrast, is designed to project onto highly contoured parts, based upon information from a 3-D model of the projection pattern.
U.S. Pat. No. 4,818,098 relates to a projection system for flat pattern to flat pattern projection. It uses multiple image position sensors for determining planar rotational and translational shifts. (See column 7, lines 20, et seq.) The summary also mentions the use of graphics processor with means to receive a variety of graphics inputs form external sources and a vector generator to provide the desired scan positions for the servos (column 8, lines 20, et seq.).
The present OLT, in contrast, is designed to project 3-D images on contoured surfaces, rather than flat surfaces, as taught in U.S. Pat. No. 4,818,098. Planar projections are a degenerate condition for the OLT. The initial OLT had quadrant detector input to detect any relative movement of the projection object with respect to the projector, and is designed to correct for these rotations and translations. The multiple sensors in U.S. Pat. No. 4,818,098 are clearly designed to compensate only for planar rotations and transitions.
It is also apparent that the use of the graphics interface by U.S. Pat. No. 4,818,098 is designed to generate a flat pattern from another data set. Again, the present OLT can be contrasted in that it does not generate an intermediate flat pattern in order to determine the commands that are sent to the galvanometers. The advantage of the present system is that distortions which can be generated by applying 3-dimensional rotations to flat pattern algorithms can be totally avoided.